For large and heavy vehicles in the so-called medium-size category, in the luxury car category, for all-terrain vehicles and for light utility vehicles, a structural form of the electrically assisted steering gear mechanism for motor vehicles is preferred in which the assistance force is introduced into the toothed rack by way of a second toothing. Steering gear mechanisms are known in which the servo drive acts on the toothed rack by means of a second steering pinion and a second toothing. Steering gear mechanisms of this kind are described in laid-open specifications DE 10 2005 022 867 A1, DE 10 2007 004 218 A1 and WO 2006/138209 A2. Said steering gear mechanisms have a relatively large structural volume since the servo drive is provided separately adjacent to the engagement arrangement between the steering pinion and the toothed rack. In addition, the guidance of the toothed rack in the region of the steering pinion has to be kept free of play by means of a thrust piece. This bearing arrangement involves production costs and constitutes a possible source of noise in practice, this being undesirable.
DE 10 2010 027 553 A1 has disclosed a double-pinion steering gear mechanism in which the two steering pinions are arranged opposite one another on the toothed rack at an angle of 90° with respect to the toothed rack. The two steering pinions are in this case mechanically positively coupled, by means of spur gears or bevel gears, for rotation in opposite directions. Owing to the geometric arrangement of the pinions in relation to one another, it is possible for a cumbersome thrust piece of the form known to date to be dispensed with. At least one steering pinion is coupled to a servomotor which assists the steering action. The rotation of the steering shaft is in this case detected by a sensor. The disadvantage of the arrangement is that shortages in structural space arise on account of the position of the servo drive and of the sensor.